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<H2><A NAME="8_15">8.15 Using background images</A></H2>
<P> Instead of having a single color background you can easily have an
 arbitrary image as the background. The image may be in either PNG, JPG
 or GIF format depending on what your installation supports.</P>
<P></P>
<HR> <SMALL>
<P><STRONG> A note on GD:</STRONG> If you are using GD 2.xx you must
 make sure that the define USE_TRUECOLOR is set to true. This is also
 the default. Failure to do so in combination with GD 2.xx will make the
 background image just look like a solid black square.</P>
</SMALL>
<HR>
<P> To use a specific image as the background you just have to use the
 method <A href="../ref/Graph.html#_GRAPH_SETBACKGROUNDIMAGE">
 Graph::SetBackgroundImage()</A> The arguments specify file-name, how
 the image should be positioned in the graph and finally the format of
 the image (if it is in JPG, PNG or GIF) format. If the format is
 specified as &quot;auto&quot; (the default) then the appropriate image format
 will be determined from the extension of the image file.</P>
<P> The file name is of course obvious but the second argument might not
 be. This arguments determine how the image should be copied onto the
 graph image. You can specify three different variants here</P>
<OL>
<LI> BGIMG_ COPY This will just copy the image unchanged onto the graph
 from the top left corner.</LI>
<LI> BGIMG_CENTER This will just copy the image unchanged onto the graph
 but it will center the image in the graph.</LI>
<LI> BGIMG_FILLFRAME This will scale the image to exactly fit the whole
 graph image.</LI>
<LI> BGIMG_FILLPLOT This will scale the image to exactly fit just the
 plot area of the graph.</LI>
</OL>
<P></P>
<P></P>
<HR><STRONG> The following section only applies to palette based images.
 True color images can NOT be manipulated this way. Applying the
 following sections to true-color images will have no affect.</STRONG>
<HR>
<P> You might often find yourself wanting to use a background image as a
 &quot;waterstamp&quot;. This usually means taking the original image, import it
 to some image editing program and then &quot;bleaching&quot; the color
 saturation, reducing the contrast and so on. Finally you save the
 modified image which you then use as a background image.</P>
<P> This whole process can be automatically accomplished in JpGraph by
 using the method <A href="../ref/Graph.html#_GRAPH_ADJBACKGROUNDIMAGE">
 Graph::AdjBackgroundImage()</A> which allow you to adjust color
 saturation, brightness and contrast of the background image.</P>
<P><DIV class="phpscript"><CODE><FONT color="#000000"> <FONT color="#0000BB">
&nbsp;$graph</FONT><FONT color="#007700">-&gt;</FONT><FONT color="#0000BB">
AdjBackgroundImage</FONT><FONT color="#007700">(...)</FONT><FONT color="#0000BB">
</FONT></FONT></CODE></DIV></P>
<P></P>
<P> to achieve the &quot;watercolor&quot; effect to avoid the image being too
 intrusive in the graph.<DIV class="example">
<BR> <A href="exframes/frame_backgroundex03.html" target="blank"><IMG border="0"
HEIGHT="200"  src="img/backgroundex03.png" WIDTH="400"></A>
<BR><B>Figure 89:</B> Example on using a watermark type background image
 <A href="exframes/frame_backgroundex03.html" target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P><DIV class="note"><B>Note:</B> The background image depicts a 1998
 Triumph Tiger. This bike is a 900cc off-road bike.</DIV></P>
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